Method and composition for removing iron stains from porcelain

ABSTRACT

A solid or liquid composition for removing iron from stains on hard, smooth surfaces, comprising (a) a sufficient amount of a hydrogen ion source to produce a pH of between about 1.5 and 4.5 under operating conditions; (b) an amount of a chelate agent sufficient to couple the Fe present in the stain, said chelate agent having a positive formation constant for Fe in the pH range of 1.5 to 4.5; (c) a soluble Fe salt in an amount less than equimolar with respect to the chelate agent; and, optionally, agents capable of producing effervescent gases; disinfectants; detergents; dyes; binders; solvents; perfumes; etc.

AU 1 EX UIIIICU mates l'illtilll 'l l Goodenough ]March 20, 1973 [54] METHOD AND COMPOSITION FOR REMOVING IRON STAINS FROM PORCELAIN [75] Inventor: Robert D. Goodenough, Midland,

Mich.

2 21 Filed: May 21,1969 21 Appl.No.: 826,389

[52] US. Cl. ..252/l05, 252/106, 252/136, 252/142, 252/147, 134/3 [51] Int. Cl. ..Clld 7/54 [58] Field of Search ..252/l05, 106, 188,136, 146,

OTHER PUBLICATIONS Chemistry of the Metal Chelate Compounds," Martell et al., 1956 page 511 Primary Examiner-Mayer Weinblatt Attorney-Griswold & Burdick, C. E. Rehberg and .1. Roger Lochhead [57] ABSTRACT A solid or liquid composition for removing iron from stains on hard, smooth surfaces, comprising (a) a sufficient amount of a hydrogen ion source to produce a pH of between about 1.5 and 4.5 under operating conditions; (b) an amount of a chelate agent sufficient to couple the Fe present in the stain, said chelate agent having a positive formation constant for Fe in the pH range of 1.5 to 4.5; (c) a soluble Fe salt in an amount less than equimolar with respect to the chelate agent; and, optionally, agents capable of producing efiervescent gases; disinfectants; detergents; dyes; binders; solvents; perfumes; etc.

9 Claims, 1 Drawing Figure METHOD AND COMPOSITION FOR REMOVING IRON STAINS FROM PORCELAIN BACKGROUND OF THE INVENTION Hard surfaces, as are typically found in the home, are easily stained when contacted with water containing Fe salts. As the water dries, the Fe is air oxidized to Fe***, which is responsible for unsightly, and tenacious, stains.

The prior art has customarily applied acidic compositions to remove such iron stains. However, in order for the removal to be satisfactory, high concentrations of strong acids, such as sulfuric acid, have been necessary. 'Naturally, this required numerous precautions while using the cleanser, and necessitated certain restrictions in its use.

U.S. Pat. No. 3,173,875 teaches the improvement of using a soluble ferrous salt along with an acid in order to allow Fe removal at a higher and safer pH.

SUMMARY OF THE INVENTION The invention comprises an improved composition and method for removing Fe from stains on hard surfaces, such as ceramic, concrete, porcelain, glass, metal surfaces and the like, based on the discovery that utilizing chelating agents and controlling pH yield unexpectedly good Fe removal results.

More particularly, the composition comprises (a) a sufficient amount of a hydrogen ion source to produce a pH of between about 1.5 and 4.5 under operating conditions; (b) a sufficient amount of a chelate agent to couple the Fe* present in the stain, said chelate agent having a positive formation constant for Fe*"* in the pH range of about 1.5 to 4.5; and, (c) a soluble Fe salt in an amount less than equimolar with respect to the amount of the chelate agent present.

The composition may be a liquid or a solid, and the invention may be utilized to clean household hard surfaces, such as lavatories, toilet bowls, floors, tile, etc.

GENERAL DESCRIPTION OF THE INVENTION The drawing illustrates the criticality of pH regarding the ability of an acid-Fe salt-chelate agent system to remove Fe present in stains. The procedure for the test is given in Example 2. Note that at a pH of between about 1.5 and about 4.5, the ability of the system to remove Fe present in stains is markedly enhanced with respect to the time necessary to remove such stains.

The solid or liquid composition of the present invention may suitably comprise to 50.0 weight percent of a hydrogen ion source which produces a pH of between 1.5 and 4.5 under operating conditions, 2.0 to

' 8.0 weight percent of a water soluble Fe salt and 14.0 to 22.0 weight percent of a chelate agent that has a positive formation constant for Fe in the pH range of 1.5 to 4.5. Optionally, agents capable of producing effervescent gases and disinfectants, detergents, dyes, binders, solvents, perfumes, etc. may be present in suitable amounts.

The hydrogen ion source may properly be an acid or an acid salt. A solid acid or acid salt is reguired for tl e solid fQ I'JIl Qf QIQQQS CT, while a liquid or solid acid or acid salt may be used for the liquid form of cleanser. Mineral acids, such as sulfuric and hydrochloric are suitable liquid acids, as are nitric, phosphoric and hydrobromic. l Alkali metal p i s t i| f 1e s and orthophosphates are suitable solid acid salts. Included among the above are NaHO LiHSO,,, KHSO, and NaH- PO,.)Sulfamic and meta phosphoric acids are examples of suitable solid acids.

Water soluble ferrous salts, mixed salts or double salts are suitable for this invention. Examples include ferrous sulfate, ferrous chloride, ferrous acetate, ferrous citrate, ferrous bromide, ferrous sulfamate, FeSO.,' H O NaHSO -H O and FeSO -Na SO,-4H O.

The free acids and the salts of chelate agents which (a) demonstrate a solubility of at least 0.1 weight percent, and which (b) demonstrate a positive formation constant (over the protonated form) for Fe**", in the pH range of 1.5 to 4.5, are suitable for the method and composition of the invention. Formation constants and the method of determining same are discussed on pages -192, Martell and Calvin, "Chemistry of Metal Chelate Compounds, Prentice Hall, Inc., New York, N. Y. (1952).

A preferred group of chelate agents are the aminocarboxylates of the formula wherein M is H, an alkali metal, ammonium or one to four carbon atoms alkyl-ammonium; R, R' and R" are independently -CH CH OH, CH COOM or CH CH COOM; A is an alkylene radical of two or three carbon atoms; and n is an integer of from 0 to 4.

Examples of the above preferred group include diethylenetriaminepentaacetic acid (DTPA ethylenediaminetetraacetic acid (EDTA nitrilotriacetic acid (NTA), N-hydroxyethylenediaminetriacetic acid (HEDTA), and the Li, Na, K and ammonium salts thereof, such as Na H EDTA, Nail, EDTA and Na: NTA.

The solid form of the invention has the advantages of being stable and easily handled, and is, therefore, the preferred form. The Fe chelate forms in situ when using the solid. This embodiment can suitably include:

- A. 35 to 55 weight percent of a solid acid or acid salt as defined above;

B. 20 to 30 weight percent of a solid carbonate or bicarbonate of an alkali or alkaline earth metal capable of producing a soluble salt of (A) above in the pH range of 1.5 to 4.5, which produces, in contact with said hydrogen ion source, an effervescent C. 15 to 25 weight percent of a chelate agent as defined above;

D. 5 to 10 weight percent of a ferrous salt as defined above; and

E. Disinfectants, detergents, lubricants, binders, perfumes and dyes in amounts necessary to fulfill the desired functions.

More particularly, the solid form of the composition may suitably contain the following components:

A. 40 to 50 weight percent of a solid acid oracid salt, such a s an alkaliflflmetal bisulfate or orthophosphate, or sulfamic acid;

B. 22 to 26 weight percent of a solid alkali or alkaline earth carbonate or bicarbonate, such as Na, K, Li, Mg or ammonium carbonate or bicarbonate, or FeCO C. 17 to 21 weight percent of one of the above defined chelate agents;

D. 5 to 7 weight percent of FeSO H O NaHSOfl-l O, FeSO Na,SO '4ll O, FeCO or Fe(SO -,-NH )2;

E. 2 .to 4 weight percent of a disinfectant that is a solid and has a pKa greater than about 4.5, such as o-phenylphenol, 3 ,4,5-tribromosalicylanilide;

F. 0.2 to 0.3 weight percent of an anionic or nonionic surfactant or a mixture thereof, that is solid or liquid, but not contained in a water or short chain aliphatic alcohol base, and is stable in the operative pH range, such as sodium lauryl sulfate or the Na salt of dodecylated oxydibenzene disulfonate;

G. 1 to 2 weight percent of a perfume that is a solid or liquid, such as an oil, but not one that is contained in a water or short chain aliphatic alcohol base; and

H. 0.01 to 0.02 weight percent of a dye that is stable in the pH range ofabout 1.5 to 4.5.

The embodiment of the invention wherein the form is liquid can suitably include:

1. 1.5 to 2.5 weight percent of a mineral acid as defined above;

10 to 22 weight percent of a chelate agent as defined above;

3. l to 3.5 weight percent of a ferrous salt as defined above;

4. 3 to 6 weight percent of a reducing agent capable of reduding Fe to Fe in the pH range of 1.5 to 4.5 and, thereby, stabilizing the liquid form from Fe oxidation before use;

5. 30 to 60 weight percent of an aliphatic short chain alcohol, i.e., one to about four carbons, as a solvent; and

6. Disinfectants, detergents, lubricants, etc. in amounts necessary to fulfill the desired functions.

More particularly, the liquid form of the composition may suitably contain the following components:

A. 1.7 to 2.2 weight percent of a mineral acid, such as hydrochloric, sulfuric, sulfamic hydrobromic or phosphoric acid;

B. 14 to 18 weight percent of one of the above defined chelate agents;

C. 2 to 3 weight percent of a ferrous salt, such as ferrous sulfate, ferrous chloride, ferrous acetate, ferrous citrate, ferrous bromide, or ferrous sulfamate;

D. 4 to 5 weight percent of a reducing agent, such as sodium hydrosulfite, hydroxylamine hydrochloride, sodium hypophosphite;

E. 40 to 50 weight percent of a short chain aliphatic alcohol, such as methanol, ethanol, i-propanol, npropanol or n-butanol;

F. l to 2 weight percent of a detergent, or mixtures thereof, such as are used for the solid form;

G. l to 2 weight percent of an anionic phenolic disinfectant, either solid and liquid, such as o-phenylphenol, 3,4,5-tribromosalicylanilide; and

H. Perfumes and dyes such as those used in the liquid embodiment and in similar amounts.

SPECIFIC EMBODIMENTS Example 1 The iron staining procedure practiced in US. Pat. No. 3,173,875 was used to test examples of the compositions of the instant invention. A 5 percent ferric chloride solution was applied to a glazed porcelain wall tile and baked on at 130C. for 2 hours. A very tenacious rust colored stain resulted, which could not be rubbed off with a wet cloth.

The ability of any formulation to remove such a stain was tested by (l) placing a stained tile in a beaker containing three liters of water and adding the solid formulation or (2) placing one drop of the liquid formulation on the stain in the case of the liquid formulation. The time necessary to completely remove the stain from the time of first contact was then noted.

An example was formulated as follows:

30.00 gm. NaHSO,

18.82 gm. NaHCO 15.00 gm. N821": EDTA 10.98 gm. NaHSOA-I O FeSO -H O 2.40 gm. o-Phenylphenol 0.75 gm. Perfume 0.19 gm. Na salt of dodecylated oxibenzene disulfonate 0.01 gm. Turquoise dye (an acid stable copper phthalocyanine dye) This formulation was dry blended and compacted into a tablet at a pressure of 3,000 p.s.i. It was then placed into the beaker as taught above, and, after effervescing vigorously, removed the iron stain in less than 3 minutes.

A further example (liquid) was formulated as followsi 7.00 gm. Na,n,Po,-H,o

71.60 gm. H O

24.30 gm. Na, DTPA 2.80 gm. H,SO (Conc.)

6.80 gm. FeSO -7H,O

36.00 gm. Methanol 0.75 gm. Na salt of dodecylated dibenzene disulfonate 0.75 gm. o-Phenylphenol This formulation was tested as a liquid as described above, the one drop cleaning the iron stain in the area of tile contacted in less than 2 minutes.

Example 2 An experiment was carried out to determine the criticality of pH on the ability of the composition of this invention to remove Fe stains.

The stained material was prepared by completely wetting flux calcined diatomaceous earth with 0.3 M FeCl which contained Fe as a radioactive tracer. NH was then blown through the bed to precipitate hydrous Fe O the sample dried at l 10C., washed several times with deionized water and aged for 2 25 weeks in water at C. Analysis showed that one gram of the supported ferric oxide contained about 0.6 millimoles of iron.

About 30 mg. of supported ferric oxide was treated in each run. The indicated solvent (25C.) was pumped through the bed at about 10 ml./min., and standard radioactive iron tracing techniques were used to rate of decay of activity, and, hence, the rate of dissolution of Fe o could be easily determined.

The results are expressed as the half time (t of the dissolution reaction, i.e., the time required to reduce the activity of the sample to half its initial volume. As a basis for comparison, it should be noted that the half time of dissolution of the mo, sample employed in these experiments was found to be 24 minutes in 3M HCl.

The results are given in FIG. 1.

lclaim:

1. An improved composition for removing Fe from stains comprising:

A. A sufficient amount of a hydrogen ion source to produce a pH of between about 1.5 and 4.5 under operating conditions;

B. A sufficient amount of a chelate agent to couple the Fe" present in the stain, said chelate agent having a positive formation constant for Fe in the pH range of about 1.5 to 4.5; and

C. A soluble Fe salt in an amount less than equimolar with respect to the amount of the chelate agent present.

2. The composition of claim 1 wherein the amount of acid is 1.0 to 50.0 weight percent, the amount of Fe salt is 2.0 to 8.0 weight percent, and the amount of chelate agent is 1.4.0 to 22.0 weight percent.

3. The composition of claim 1 which comprises:

A. 35 to 55 weight percent of component (A) in the form of a solid acid or acid salt;

B. to 25 weight percent of component (B);

C. 5 to 10 weight percent of component (C); and

further,

D. to 30 weight percent of a solid carbonate or bicarbonate of an alkali metal, an alkaline earth metal & ammonium, capable of producing a soluble salt of (A) above in the pH range of 1.5 to 4.5 and which produces, in contact with said H ion source, an effervescent gas.

4. The composition of claim 1 which comprises:

A. 1.5 to 2.5 weight percent of component (A) in the form of a mineral acid;

B. 10 to 22 weight percent of component (B);

C. l to 3.5 weight percent of component (C);

D. 3 to 6 weight percent of a reducing agent capable of reducing Fe to Fe in the pH range of about 1.5 to 4.5;

E. 30 to 60 weight percent of an aliphatic short chain alcohol of one to about four carbon atoms.

5. The composition of claim 1 wherein the chelate agent is diethylenetriaminepentaacetic acid; ethylenediaminctetraacetic acid; nitrilotriacetic acid; N-hydroxyethylenediaminetriacetic acid; or the Li, Na, K or Nl-L salts thereof.

6. The composition of claim 3 which comprises:

A. 40 to 50 weight percent of an alkali metal bisulfate, alkali metal orthophosphate, alkali metal metaphosphate or sulfamic acid;

B. 17 to 21 weight percent of component (B);

D. 22 to 26 weight percent of Na, X, Li, Mg or ammonium carbonate or bicarbonate, or F eCO 7. The composition of claim 4 which com rises: A. 1.7 to 2.2 weight percent of CHl, H 0 l-lBr or B. 14 to 18 weight percent of component (B);

C. 2 to 3 weight percent of ferrous sulfate, chloride,

acetate, citrate, bromide or sulfamate;

D. 4 to 5 weight percent of sodium hydrosulfite, hydroxylamine hydrochloride or sodium hypophosphite;

E. 40 to 50 weight percent of methanol, ethanol, i-

propanol, n-propanol or n-butanol.

8. An improved process for removing Fe from stains on hard surfaces which comprises contacting said stained surface with an effective amount of the composition of claim 1.

9. An improved process for removing Fe from stains on hard surfaces which comprises contacting said surface with an effective amount of the composition of claim3.

UNITED STATES PATENT OFFICE 1 CERTIFICATE OF CORRECTION o Patent No. 3,721,629 Dated M r h r), 1973 Inventor(s) Robert D. Goodenough It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 4, "Hal-I0 should be --N&HSO

Col. 6, line 25; in Claim 7 "cm" shouldwbe --HCl--.

Signed and sealed this 31st day of Ju1y .1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer 7 Acting Commissionertof Patents 

2. The composition of claim 1 wherein the amount of acid is 1.0 to 50.0 weight percent, the amount of Fe salt is 2.0 to 8.0 weight percent, and the amount of chelate agent is 14.0 to 22.0 weight percent.
 3. The composition of claim 1 which comprises: A. 35 to 55 weight percent of component (A) in the form of a solid acid or acid salt; B. 15 to 25 weight percent of component (B); C. 5 to 10 weight percent of component (C); and further, D. 20 to 30 weighT percent of a solid carbonate or bicarbonate of an alkali metal, an alkaline earth metal or ammonium, capable of producing a soluble salt of (A) above in the pH range of 1.5 to 4.5 and which produces, in contact with said H ion source, an effervescent gas.
 4. The composition of claim 1 which comprises: A. 1.5 to 2.5 weight percent of component (A) in the form of a mineral acid; B. 10 to 22 weight percent of component (B); C. 1 to 3.5 weight percent of component (C); D. 3 to 6 weight percent of a reducing agent capable of reducing Fe to Fe in the pH range of about 1.5 to 4.5; E. 30 to 60 weight percent of an aliphatic short chain alcohol of one to about four carbon atoms.
 5. The composition of claim 1 wherein the chelate agent is diethylenetriaminepentaacetic acid; ethylenediaminetetraacetic acid; nitrilotriacetic acid; N-hydroxyethylenediaminetriacetic acid; or the Li, Na, K or NH4 salts thereof.
 6. The composition of claim 3 which comprises: A. 40 to 50 weight percent of an alkali metal bisulfate, alkali metal orthophosphate, alkali metal metaphosphate or sulfamic acid; B. 17 to 21 weight percent of component (B); C. 5 to 7 weight percent of FeSO4.H2O + NaHSO4.H2O; FeSO4. Na2SO4.4H2O; FeCO3; or Fe(SO3-NH2)2; D. 22 to 26 weight percent of Na, K, Li, Mg or ammonium carbonate or bicarbonate, or FeCO3.
 7. The composition of claim 4 which comprises: A. 1.7 to 2.2 weight percent of CHl, H2SO4, HBr or H3PO4; B. 14 to 18 weight percent of component (B); C. 2 to 3 weight percent of ferrous sulfate, chloride, acetate, citrate, bromide or sulfamate; D. 4 to 5 weight percent of sodium hydrosulfite, hydroxylamine hydrochloride or sodium hypophosphite; E. 40 to 50 weight percent of methanol, ethanol, i-propanol, n-propanol or n-butanol.
 8. An improved process for removing Fe from stains on hard surfaces which comprises contacting said stained surface with an effective amount of the composition of claim
 1. 9. An improved process for removing Fe from stains on hard surfaces which comprises contacting said surface with an effective amount of the composition of claim
 3. 